新型AgC5电触头材料的性能及显微组织

采用高能球磨．还原剂液相喷雾化学包覆．粉末冶金工艺制备出新型银石墨电触头材料AgC5(质量分数)。经与烧结挤压和机械混粉工艺的同类触头相对比，该材料具有优异的机械物理性能。电磨损分断对比试验发现，与常规机械混粉同类触头相比该材料的耐电腐蚀性能提高了40％以上。利用扫描电镜和金相显微镜对AgC包覆粉体及烧结复压后触头显微组织进行了分析，发现微米尺寸的Ag颗粒呈絮凝状结构包覆在石墨片外，这种絮凝体内部孔洞尺寸细小且分布均匀；新工艺材料组织细腻，球磨石墨均匀分布在Ag基体上，弥散度较高。材料经电弧作用后的工作面用SEM和EDS分析发现：新工艺改善了Ag与C间的润湿性和物理结合强度，在电弧瞬时高温作用后，熔融Ag能够以珠状粘附在基体表面，有助于减少Ag液的喷溅损失。

Properties and Microstructure of a Newly Developed AgC Electrical Contact Material

A newly developed Ag5wt%C electrical contact material was fabricated using the technique of high-energy in conjunction with reductant liquid spraying chemical coating and powder metallurgy. Compared with its conventional counterparts made from traditional blending and extrusion, the new contact material has excellent physical and mechanical properties. Contact-erosion experiments were performed using an ASTM Contact Material Automatic Measuring Device. The experimental results indicated that the arc erosion resistance of the newly developed Ag5wt%C material was more than 40% higher than that of the conventionally blended counterpart. The microstructures of the AgC coating powder and the sintered-pressed sample were characterized by SEM and metallographic microscopy. The surface morphologies of the two types of Ag5wt%C contact after breaking arc melting were examined by SEM together with EDS. It was found that the melted Ag particles produced by arc thermal shock become spherical and adhered to the matrix, thereby decreasing the splattering loss of Ag. The wettability and interfacial strength between silver and graphite were much improved as a result of using the new technique. The newly developed AgC may substitute for those counterparts made from extrusion or blending as a new electrical contact material.